1. Field of the Invention
The present invention relates to an optical sensor and method of making the same, and more particularly, to a silicon-rich dielectric photosensitive device using silicon-rich dielectric layer as a photosensitive layer, and method of making the same.
2. Description of the Prior Art
Due to the novel applications of fiber-optic communication and various types of thin film transistor (TFT) display, the requirement for optical sensors or receivers is according increasing. The conventional optical sensor uses III A group element and V A group element to form PN (P-type dopant/N-type dopant) junction sensor or PIN (P-type dopant/intrinsic/N-type dopant) junction sensor. The PN/PIN junction sensor, however, is based on indirect energy gap mechanism, which has low optical absorption efficiency. Also, the conventional PN/PIN junction sensor is apt to be influenced by non-target light source, and therefore has high bias. In the fabrication of TFT displays, the PN/PIN junction sensor made of III A group element and V A group element and the TFT have problems in process compatibility. In addition, the PN/PIN junction sensor is formed adjacent to peripheral circuits, which may generate signal interference and lead to a trade-off between the aperture ratio and photosensitive efficiency in design. Based on the aforementioned reasons, PN/PIN junction sensor can no longer fulfill the requirement in many opto-electronic applications.